Some bathtubs, lavatory sinks, toilet bowls, and the like have the surfaces of their substrates covered with a glassy layer of glaze, enamel, or the like in order to densify and protect their surfaces. On the other hand, there has been an increasing need for an exterior with a good design that provides a harmony in the space as a whole. Thus, there has been a demand to express a matted, soft exterior besides the glossiness of the glassy layer.
JP H06-191920 A describes a method of manufacturing a ceramic ware involving sintering the ceramic ware with its surface matted. In this method, in the sintering process, alumina in the glaze is separated and small alumina crystals are deposited on the surface of the ceramic ware to mat the surface.
JP 2012-46364 A describes a sanitary ceramic ware having an antifouling matted surface. In this sanitary ceramic ware, crystal particles are deposited by glaze sintering so as to form a matted surface having an Rc (mean height) of 0.5 μm to 2.5 μm, an Rc/RSm (mean length) more than 9×10−3 and less than 16×10−3, and a glossiness of 25 to 51. In this way, both an antifouling property and mat feeling are achieved.
JP H08-133870 A describes a method of manufacturing a glazed product. In this method, a glazed surface is subjected to blasting and then sintered at a temperature higher than the softening temperature of the glaze but lower than a sintering temperature. In this way, both an antifouling property and mat feeling are achieved.
JP 2010-120232 A describes a method involving performing blasting on a glazed surface, and then performing electron beam machining, laser machining, or plasma machining on the glazed surface to smoothen its sharp asperities to impart an antifouling property to the glazed surface.